The present invention relates to hermetic sealing of an implantable medical device, and particularly to a wafer level hermetic seal for an implantable medical device that employs a microelectromechanical system (MEMS).
Implantable medical devices (IMDs) employ internal electronic circuitry that is hermetically sealed in a biostable package. This internal electronic circuitry is typically implemented as one or more integrated circuits (ICs). More recently, the prospect of implementing switching circuitry as a MEMS system has been considered, as discussed in U.S. application Ser. No. 10/973,117 filed Oct. 26, 2004 for “MEMS Switching Circuit and Method for an Implantable Medical Device” by R. Receveur et al., which is hereby incorporated by reference. However, a MEMS is more difficult to employ in an implantable medical device than a system that employs only ICs, at least in part because of the more stringent packaging requirements to provide a particular environment around the MEMS. In addition, a MEMS package may need to redistribute electrical signals, provide mechanical support, handle power and provide thermal management functions. These considerations present challenges in designing an effective and efficiently manufacturable sealed MEMS package for an IMD.
Accordingly, there is a need in the art for an improved packaging solution for MEMS devices employed in implantable medical devices.